This invention relates to torque wrenches which are powered by hydraulic fluid delivered by a pump. More particularly, this invention relates to a calibration test stand and method in which the pump and the wrench are mutually calibrated to determine the necessary pump output to achieve a desired torque from the wrench.
Hydraulically powered torque wrenches are well known in the art. A particularly useful kind of torque wrench is the type shown in U.S. Pat. No. 3,745,858, the disclosure of which is incorporated herein by reference. These torque wrenches are powered by hydraulic fluid from a pump which is connected to operate the power piston of the wrench. In using these wrenches, the typical approach in the prior art is to consult a chart which tells the user to set the pressure level of the pump to deliver hydraulic fluid at X psi to obtain Y torque output from the wrench. This typical prior art approach is susceptible to considerable inaccuracies from sources such as pump errors, gauge errors, etc.